Ensure that injection pressures are appropriate (under 70 MPa [10,000 psi]). The main causes for short shots are inappropriate injection pressure and speed. After an hour of running, the steel temperature stabilized at 78°F. Weld lines represent the region where two separated melt fronts recombine. 010 0. The position, length, and angle of weld lines are dependent on the. 2. The polymer material is melted by the heat from the heaters and viscous heating due to the screw rotation in the plasticization stage as shown in Fig. At the high end of SOLIDWORKS Plastics simulation in Plastics Premium, mold-level analysis can be performed by representing the runners, cooling channels and a mold body around the cavity. Help prevent warping with these measures: Raise the mold or material cylinder temperature. Thus, as the flow continues, the two flow fronts may gradually rejoin to make one uninterrupted flow front. Some of these factors could be the flow rate, the pressure, or the temperature settings of plastic injection molding. GPM: Measuring the amount of water passing through the mold every minute is a key measurable in determining turbulent flow. Sources of defect: Material: Material too high viscosity; Method: Injection speed in the critical area too high (too low)Flow lines are one of the most common problems with injection molding. Mold makers should also pay attention to sprue, runner, or gate design. The problem could be the result of machine settings made before the gate was installed. injection molding. 3) Poor Preventative Maintenance. . Kobayashi et al. There are several factors that can contribute to the formation of weld lines, including: Part design: The design of the part can impact the flow of the material and the likelihood of weld lines forming. The type of gate for manufacturing often depends on the material used and the parts’ shape. Mold flow analysis is a powerful tool for optimizing the design and performance of injection molding processes. This injection molding defect appears as black or rust-colored discoloration on the molded part's surface or edge. Spatter lines formed on the surface of the plastic along the direction of melt flow are called silver marks. These knit lines are formed as molten plastic in the injection mold flows around an obstruction like a feature. Flow lines – A common plastic injection molding defect in which discolored ring-shaped streaks, patterns, or wavy lines appear around gates or narrow sections of the finished product. Thin walls often increase the pressure required to fill the part, and. Some of the most popular brands include:Fiber reinforced thermoplastics (FRTP), reinforced with glass or carbon fibers, are used to improve the mechanical strength of injection-molded products. New design is said to eliminate mold damage from nozzle stringing or work-arounds that slow cycles. Flow Lines: Flow lines on thinner areas of molded components appear as a wavy pattern, often a different color than the surrounding area. This study focus on the formation of weld lines of molten polypropylene and. Flow lines, also referred to as flow marks or weld lines, are visible lines or patterns on the surface of a plastic component. Reducing the dimensions of the runner system. 5. This is achieved by using the needle valve nozzles to control mould filling so that only one flow front exists at a time. Injection molding, in addition to extrusion, is the most important technology in the polymer processing industry. The Problems & Solutions course is designed to train in the recognition and analysis. Flow lines are surface irregularities, wavy patterns, or a rippled effect, perhaps of a slightly different color, that can appear in injection molded parts. Adjustments to injection speeds are the best way to determine which of these two are the specific cause. Flow marks, also known as flow lines or weld lines, are common defects that can occur in plastic molded parts. These properties make it ideal for. Mold flow marks, also known as flow lines or weld lines, are often caused by variations in the flow of molten plastic material during the injection molding process. 750 in. Using a thermoplastic that stays in a. When two or more streams of plastic meet and fuse together, a visible line or weakness is formed on the surface of the finished product. Its popularity is typified by the numerous products produced in this way at the present time. By contrast, a slow injection speed will give you a matte finish and a cold mold, such as 50F, will give you a more flexible part. These defects are not visible, like small. What it is:Jan 04, 1999. Lastly, you can only acquire the benefits of parting lines in injection molding during plastic production if you design the parting line correctly. Lower speeds allow gas more time to escape through vents. 16″) will be difficult to inject, leading to flow lines, surface imperfections, and short shots. Here are some common remedies for flow lines in injection-molded products: Increase the injection speed, pressure and material temperature to ensure the material fills the mold before cooling. For optimal cooling, these waterlines are located as close as possible to the surface of the molded part. The speed of an injection moldingRepeat the two previous steps two or three times, starving the screw periodically to allow the screw to rotate without building a shot. Heat Input and Cooling Calculator for Injection Molding. 5. Melt delivery management has a major impact on final part quality and the ultimate success of the production line. RapidDirect – Your Best Injection Molding Partner. This design is deliberate in order to help the mold. The Plastic Troubleshooter Defect - Flow Lines. Unexpected flow lines, so-called tear drops, occur. 015 0. Check that the machine is creating enough clamping force to keep the mold halves together. The mold material 6 can have several effects on. We will now look at the problem you are likely to encounter and how to fix them. Flow lines were created during injection moulding process. In some areas, the option is evident, while in others, it. FIG 1 Depiction of fountain flow. industry, to deliver intuitive injection mold-ing simulations embedded in NX. Prevent Flow and Knit Lines During the Injection Molding Process. Short shots refer to incomplete filling of a mold cavity. The line actually indicates the parting ‘plane’ that passes through the part. In injection molding weldlines are generated when two separate melt streams join either. In manufacturing, the Weld line or Knit line or Meld line is the line where two flow fronts meet when there is the inability of two or more flow fronts to "knit" together, or "weld", during the molding process. If during the design and development stage,. A weld line refers to a line, notch or color change that is created on the molded part caused by the convergence of two separate flows of molten plastic. (1) Reduction of injection time and shortening of the molding cycle. to 0. Picture the flow of a liquid resin filled with, for example, glass fiber. The article has been structured just for you to gain an understanding of the same so that when you plan to buy plastic injection molding, you do understand what it means to do so. Weld lines are formed during cavity filling whenever two separated melt flow font recombine. Hamstra: For the OEMs, having a good baseline of what our cooling flow and temperature through a mold is going to give us a good optimization into the next supply chain for the injection molders. (3) Improving the surface gloss of the product. The mold flow model is usually a single-part model, that is, the FRT part itself, but the mechanics model is often a multi-part model, an assembly of the FRT part and others. 008 to 0. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Strengthening. This method can be helpful in. These benzene rings also increase the viscosity, reduce shrink rate, and increase strength with the exception of knit and/or meld lines. A knit line in a plastic injection-molded part is created when two separate plastic flows meet within the mold and "resolidify" along their interface. The co-simulation of mold flow and structure plays an important role in the design of injection molded fiber-reinforced thermoplastic (FRT) parts. Randy Kerkstra has been in the plastics industry for more than 26 years, occupied frequently with troubleshooting injection molding. There are important differences between an injection mold sprue and its runner system. Leadtime Leader 2024. Solution: If possible, operate the machine on. Complexities in the design and intricate pathways in the mold can also create flash in injection molded parts. (All Illustrations: S. (All Illustrations: S. Also called “Weld Line. They are typically the same color as the part but are a different tone. In injection molding weld lines are formed whenever two flow fronts are joined. 1. Flow marks: Flow lines Directionally "off tone" wavy lines or patterns Injection speeds too slow (the plastic has cooled down. One way to reduce the changes in speed of the flow front is to tailor the injection-speed profile. 750 in. If I can answer any questions you may have on optimizing the plastic part design, CNC plastic prototype, mold manufacturing, and injection molding or if I can be of any other help, please feel. They usually are a slightly different color than the rest of the piece, and typically occur on more narrow sections of the molded item. Obviously, as the resin front moves through the mold, the fill material will always be behind the front. Because you have control over exactly when and how much material enters the tool, you have tighter control of the parameters that go into making a quality part. This defect compromises aesthetics. Flow lines are lines or streaks visible on the surface of a part. Sink marks are like little craters formed on an injection-molded product. 7 of the reference. The goal when locating cooling channels in the mold is uniform mold surface temperature, which is determined by cooling channel depth and pitch. Increase the mold temperature. The wall thicknesses of an injection molded part generally range from 2mm – 4mm (0. Injection molding could develop knit lines if one front cools before it reaches the other. The 7/16-inch size is a happy medium between many small lines and the fact that larger lines don’t particularly increase the heat exchange benefit. 5. Flow fronts moving too slowly can lead to pressure in front of a flow front being too low to force gas through vents. Injection molding flow lines can also be caused by using material that has defects. This can be achieved by connecting ribs to each other. Weld lines in injection molding are formed when two or more flow fronts of molten plastic material meet and merge during the molding process. also utilized the co-injection molding technique to study the flow of polypropylene at the weld line behind an obstacle in injection molding; the weld line can be seen clearly from the Fig. It can also aid in material selection since fill. Below are ways through which you can remove and prevent flow lines; a. Let’s review some methods to prevent flow and knit lines in plastic injection molding. Just multiply the area of the barrel × the injection velocity. If the mold itself has cracks or defects, the finished product will also have various problems. MFR values for polypropylenes are determined at the same load but at a higher temperature 230°C (446°F). Mold Design. If necessary, the mold designer may simulate the flow of solidification of resin using an injection molding simulation program. PartWeld lines form where two or more flow fronts come together and can create a cosmetic or structural problem. flow rate, in turn, causes the heat transfer effi ciency of the cooling cha nnels to vary from one. Mold is not vented properly causing slow flow at knit lines. ”Poor venting, along with the diesel effect, can also cause the mold to wear on the mold parting lines, resulting in flash (excess plastic) on the injected part. INADEQUATE INJECTION PRESSURE. On a small four-cavity tool, the part had a U-shaped notch in the center. This article explains the causes and. However, you can easily prevent such defects by simply adjusting the temperature, flow rate, or other mold parameters. More Control. Mold flow analysis is a software-enabled process that. Quality concerns in injection-molded materials can vary fr. Plastic Injection Molding Defects series-Flow Marks or Flow Lines Aug 23, 2019 What should we keep in mind when designing for injection molding?1. b. After discussing the injection molding learning process and the underpinning philosophy in the first two parts of this series, Bill Tobin gets to the heart of the matter—the mold—and shares a few tricks of the trade. The gate in injection molding is an essential component that directly connects to the plastic part and controls the flow of melted plastic resin into the cavity. Mold surface is too cold. They are the result of fundamental physical effects taking place inside of the mold. The flow line is usually connected to injection specifications, mold and injection material, it can be defined as linear grooving, or round surges, on the surface of an injection molded part that shows the instructions of product flow within the cavity of the mold. 010 0. They are best described as "off tone" wavy lines/streaks or patterns in the molded part around the injection ports. When designing a new injection mold, a moldmaker’s main goal should be to put its client in the best position to make quality parts consistently and efficiently. The leading edge of the flow, or the melt. c. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. As a result this weld line will be a weak point in this part. It is crucial to manage flow lines to ensure. Co-injection molding technique is a useful way to study weld lines, which can offer more detailed information of the. Bubbles are caused by melting flow fronts colliding in a mold cavity. The part surface was observed in reflected light using optical microscope and the pictures of. 7 in Kobayashi et al. As discussed above, one of the things that contribute to plastic injection molding defects like sink marks and flow lines is the type of injection molding machine used. Co-injection molding technique is a useful way to study weld lines, which can offer more detailed information of the. The accompanying table lists the flow rates for various barrel diameters at various injection velocities. Flow Lines and Flow Marks. By altering the part design, it may be possible to just have one flow front, and avoid multiple flow fronts having to come together. The weld line and the flow pattern of co-injection molding can be seen from Fig. The weld-lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms. Kulkarni) During the fill phase (Fig. Increase the injection speed. Polycarbonate is a tough, optically clear or opaque, biocompatible plastic with good thermal resistance. This. The best we can hope for is to pressurize the knit or meld line better through the combination of melt temperature, mold temperature, flow rate, and holding pressure. diverse parameters of the injection-molding process, needs a lot of experience in order to achieve optimum results, especially if. These flow fronts occur when the molten plastic material encounters obstacles, such as inserts, ribs, or other features within the mold cavity. If a mold cavity has a significant flow length-to-thickness ratio, the material should have a low enough viscosity to enable a continuous flow. ” Flow marks do not affect component integrity. Midland, MI. As a result, the lower degree of stress when gating with valve gate systems becomes relevant. Peering into the Flow. They are caused by improper bonding and low injection pressure and speed [ 46 ]. How to solve flow lines in injection molded products?Injection molding is a heat-transfer process. There are three stages of flow – laminar, transient and turbulent. So what does the 140F mold temperature give us? The molding technician thought the 140F mold water was OK because the data sheet provided by the material supplier suggested mold temperatures from 75 to 180F. The formation of weld lines and their location along the flow path is a well-studied phenomenon in conventional injection molding; however, only a few papers are devoted to micro-injection molding [11,13,14,15,16]. The molding process is the leading cause of defects in injection molding parts. From the perspective of the mold, when the molten plastic reaches the gate through a larger-sized runner, the flow resistance of the melt is greatly increased because the gate size is usually very small. At a theoretical flow distance of 10 mm it represented the measured values well but at a longer distance it underestimated the experimental scale. Steven. In addition, when the melt is solidified in the cavity, there is a vacuum between the product and the cavity wall, also the air must enter the mold. For injection molding grades, the MFR (MI) values for polyethylenes are generally determined at 190°C (374°F) using a static load of 2,160 g. You can avoid having any weld lines with cascade injection moulding. Flow lines, also referred to as flow marks or weld lines, are visible lines or patterns on the surface of a plastic component. 1 m/s, and a zero-shear-rate viscosity η 0 (T 0)=3760 Pas. tall, and 0. One exception: ribs should be about 50. On-Line Solutions To Injection Molding Problems. These flaws might have an impact on the product’s functionality as well as its appearance. 10(a) (please see Fig. For each investigated mould temperature, a linear relationship can be observed. The most important factors to consider during molding are the mold temperature, melt temperature, and injection pressure and speed. Flow lines are a typical problem for injection molding faults that appear as visible streaks or lines on the surface of the molded part. The type of resin used during injection molding plays a large role in whether or not a knit line will be present. 1 – In plastic injection molding, the flow ratio is the distance molten plastic must travel, divided by the wall thickness of the part. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. A look at how taking the time and data to analyze a mold problem will help you repair it right—and permanently—the first time. Depending on the resin, resin temperature, mold temperature, and filling speed, knit lines can vary. In other words, the long-chain polymer. Setting the proper pressure on the injectors to push the plastic into the mold with enough speed that the plastic will coat the mold and fuse with other flow lines. 1. All mold cooling lines must have adequate flow to produce a turbulent flow condition. It explored the use of. They may also take the form of ring-shaped patterns when staying close to the mold's entry point, which is the plastic injection nozzle. How a mold is watered is key to a processor's goal of consistency. When trying to establish process control in plastic injection, watering the tool is a key variable that is often overlooked. These are off-tone streaks or lines on the surface of the plastic, and while they don’t affect the structural integrity, they are unattractive and prevent a uniform and consistent appearance. In a weld line, reinforcement fibers. FOW Mould is one of the best companies that use injection molding. A meld line occurs when two moving melt fronts converge and flow parallel to each other. The Table 2 categorically reports Melt Temperature, Injection Pressure and Injection Speed are the main contributors in the defects such as the short-shot, weld-lines, flow marks, burn-marks etc. Here’s a rundown of helpful tricks to keep in mind when designing and choosing a material for molded parts with walls: In general, ensuring your design has uniform wall thickness between 0. Note: It is applicable to thermoplastic materials only. Here are some of the most common scenarios for cracks in injection molded parts: Cracks in the Direction of Flow – If the crack develops in the direction of the plastic’s flow into the mold cavity, the cause is molecular orientation. Increasing pack or hold pressure helps to eliminate low-pressure conditions at the weld line. 5 to 2. These are typically found near the narrow sections of the mould gate and can. Round the corners of the mold where wall thickness increases to help keep flow rate consistent and prevent flow lines. They are visible on one side of the parts. WeInjection molding is the most widely used form of plastics processing worldwide. Bob Hatch is manager of technical service and customer support for Prime Alliance, the Des Moines-based resin distributor. The material is poured into a mold, which shapes the size and looks of the article. The difference between a knit and meld line is significant, dramatically impacting the part’s structural integrity. But add 30% glass and weld-line strength retention drops to only 34% as high as the compound with no. Molds gain streaks through molten plastic cooling and solidifying at different rates. Commercial injection molding simulation packages, such as Moldflow and C-MOLD, have been incorporating GAIM options to provide computerized design and optimization tools for GAIM processes and. Investigate the mold for signs that a water leak is present, and correct the condition. Flow lines are. They appear as waves or lines, usually of a different color tone from the surrounding area. Consider the following examples of cooling channel configurations in P20 mold steel with a water line diameter (D) of 11. Haagh, in Encyclopedia of Materials: Science and Technology, 2001 3 Modeling. The steel that cored out and created the notch was very thin—roughly 0. Unraveling Flow Lines. Causes: The issue might be varying flow rates as the molten plastic moves through the mold or changes in the thickness of the mold’s walls. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. 150 in. Parting Lines. This “inside-out” flow of the plastic mimics the flow in a water fountain, therefore it is called fountain flow. Flow lines. Cascade Moulding Avoids Weld Lines. (1. Sink Marks. The co-simulation of mold flow and structure plays an important role in the design of injection molded fiber-reinforced thermoplastic (FRT) parts. Definition: Off-tone streaks, patterns or lines that appear on parts. Polymer Injection Molding: Gas-assisted Molding. Investigate the mold for signs that a water leak is present, and correct the condition. Flow lines or flow marks are a common visual defect in injection molding. These are caused by the shot of molten plastic moving at different speeds throughout the injection mold, which ultimately causes the resin to solidify at different rates. Weld lines can compromise the strength and aesthetics of the part, so it’s important to carefully design the mold and. html. It can be difficult to determine what is truly splay, as its appearance is very similar to other defects. I’ve been noodling that question around in my head for the last three years, since injection machine suppliers like Arburg, Engel, Wittmann Battenfeld and Sumitomo (SHI) Demag started showing up at trade shows with mold-filling displays on their machine controller screens. Kobayashi et al. A ‘parting line’ is the line of separation on the plastic part where the two halves of the plastic injection mold meet. Using a thermoplastic that stays in a. google-site-verification: google03af4f4fcb62a9d5. Flow marks won. Weld lines are formed when there is an inability of two or more flow fronts to ‘knit’ or ‘weld,’ together during the molding process. Surface Delamination. For the production of these weld-line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527-2) and impact (ISO 179-1/1eU) properties were measured, and statistical analyses were performed to gain insight on the correlation between melt flow rate and weld-line behavior. Prevent Flow and Knit Lines Through Mold Adjustments. Molders should make sure the weld line is formed during the first-stage filling of the part, if possible. Incorrect gate positions cause multiple flow fronts that struggle to merge seamlessly. The formation process of weld lines can be described as. FLOW – A qualitative description of the fluidity of a plastic material during the process of molding. Figure 1 presents the shrinkage of polypropylene versus wall thickness in injection molded parts. Each needle valve nozzle opens only when the melt front has moved across its gating point. The Fill system analyzes the filling of each cavity by sensing the melt presence at the end of flow with a cavity temperature sensor and compares the fill-time. Features such as sharp corners or undercuts can. Thick sections take longer to cool than thin ones. While some molds or inserts have simple, straightforward cooling circuits, many have multiple circuits of various sizes and configurations. Countermeasures to Injection. Weld lines are a common imperfection to be found in most plastic injected molded parts. A method of melt flow visualization was used to record the weld line location on the surface of molding prepared at the proper injection conditions (method of "record grooves effect" formation. Weld lines are a kind of Achilles heel of plastics. For optimal cooling, these waterlines are located as close as possible to the surface of the molded part. Flow Rate. When the gate depth is much smaller than the cavity entrance depth, and the mold filling rate is very high, when the melt flow becomes unstable jet flow, the front jet has solidified and the later flowing melt fills the mold cavity, and the product will be Snake flow lines appear on the surface. Here are the top 5 injection molding defects that can occur, and how to solve them: Flow / Weld Lines. Check the diameter of the ejector pins and the pin hole tolerances, if the tolerance is too wide this could allow molten plastic to flow down between the pin and hole surface. Weld lines are usually pointed out as the weak region in molded parts. S. 6. Flow lines can be defined as linear grooving, or circular ripples, on the surface of a molded part that indicate the direction of material flow within the cavity of the mold. Inadequate cooling time. 120 in. 3C) is to put a vent along the entire edge, but just shy of the corners. Flow lines or marks appear as banded discolouration on the surface. As the polymer resin is injected into a mold, it flows through all parts of the mold. The emergence of silver marks is generally due to the rapid start of the injection which causes the air in the melt and mold cavity unable to be discharged quickly enough. Flow marks, also known as flow lines, are molding defects that occur in the manufacturing process of injection molding. Caused by: Non-uniform cooling times and flow rates; excessively narrow part features. This is defined for each material by the length-to-thickness (L/T) ratio of the part. Flow lines are linear grooves or circular ripples on the surface of a molded object caused by uneven cooling, improper residence time, or cycle time, or low mold. . Email Sales@Aberdeentech. As far as the mold builders are concerned, having good flow through each circuit and having a good pressure leak test that they can perform is an. When creating the parting line, the mold design is the first place to look for the appropriate parting line for an injection molded product. Flow lines are linear marks on the surface of a molded product, which indicate the flow direction of the molten plastic. Flow marks in injection molding can be avoided if adequate measures are taken. In this article, a multiscale simulation method of polymer melt injection molding filling flow is established by combining an improved smoothed particle hydrodynamics method and clustered fixed slip-link model. Weld lines are among the most critical structural defects in parts made by the injection molding of fiber-reinforced thermoplastics, explained Sirmax in a press release. For example, filled resins and ABS are more likely to. • u. Figure 7 below shows the cooling channels, defined in this case using simple sketch lines. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. Reduce the injection pressure to prevent overpacking at the gate. Minimum turbulent flow would be 12-14 GPM, while numbers in the 20’s would be identified as an excellent flow rate. Plastic is injected into a mold at a specific rate of flow—typically in. Part design features may cause a material flow to split and rejoin as it flows around design features in a mold. Precise control of resin flow, pressure and temperature is critical. Water cooling pumps coolant through lines on the outside of the mold cavity. They appear around holes or seams of an injection molded part, and some may call them “flow lines” or “weld lines”. Mold flow analysis is a software simulation that can show how resin will fill the mold during the injection molding process. 3 the path lines of selected material elements can be observed which are. Inadequate mold wall thickness leads to uneven cooling and hindered plastic flow, resulting in weld lines. 2. If the mold temperature is too low, the material temperature will drop very fast, so the injection pressure and the holding pressure will not be high enough to press the solidified layer against the mold surface, thus leaving flow lines along the melt flow direction. Flow lines appear as a wavy pattern on the surface of your plastic parts. Weld Lines-3 Ways for Detecting and Correcting. Well, what this simply implies is that injection polycarbonate molding makes it possible for you to create a wide range of part sizes. Before injection molding, there is a large amount of air in the flow path and the cavity. Flow Lines The problem with flow lines is that they. Vary injection speed, screw rpm, and backpressure. (1998) for clear photographs. After exhaustive research, testing and pilot-scale demonstration, the team developed a breakthrough new technology utilizing low constant injection pressure. If you experience flash on your injection blow molding products, consider redesigning a worn out or faulty mold. In this study, a fully automated. Higher numbers assure that water flow is adequate, and that turbulent flow is at an acceptable level. Our glossary of terms provides definitions for a wide range of injection molding terms. In manufacturing, the Weld line or Knit line or Meld line is the line where two flow fronts meet when there is the inability of two or more flow fronts to "knit" together, or "weld", during the molding process. Manifesting as wavy lines or streaks on the surface of the molding, flow lines generally occur when molten material flows. Flow lines are unwanted streaks, waves, or lines on a part’s surface. Select a plastic that is less prone to shrinkage. 100 to 0. The material is kept poured into the mold for some time. If larger gates are used, expect a longer molding cycle time. Within more basic plastic part design plans this plane can be a simple, flat surface, but it is often a complex form that. Avoid knit lines when designing a molded part to improve cosmetic appearance and functionality. Each material has a maximum flow length for a given injection pressure and wall thickness — this is known as the flow ratio. 1 Caused By The Quality of Injection Mold. Impurities in the resin will prevent a smooth flow through the mold. A poorly designed or maintained water-cooling system can have a serious impact on production efficiency and cause many maintenance issues. Results have shown that, although anisotropy is more pronounced in injection moldings, the mean of values for modulus along and at 90° to radial mold flow lines of an optimum modulus cure are the. Increasing injection speed. Errors like these manifest when processing is done incorrectly. 004 m, a characteristic velocity ν 0 =0. Each gate type has specifications that significantly affect the end product’s structure and appearance. For the measurement of the crystallinity a DSC analysis was performed. Allows you to accommodate a variety of part sizes. When two or more strands of molten plastics meet in the mold, a weld line will be produced at the junction [1,2]. By using proven methods for cooling line design, warp and cooling time are minimized. For the production of these weld-line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527-2) and impact (ISO 179-1/1eU) properties were measured, and statistical analyses were performed to gain insight on the correlation between melt flow rate and weld-line behavior.